There is known a motor-driven screwdriver having an indicating device that informs a worker about the drive status of the motor-driven screwdriver (Patent Literature 1). The known motor-driven screwdriver has a motor-driven screwdriver body equipped with an LED indicating that the associated motor is being driven and another LED indicating a state where the motor has been stopped due to the generation of torque greater than a specified value, thereby enabling visual confirmation of the motor drive status.
There is also a motor-driven screwdriver that, unlike the above-described motor-driven screwdriver, does not incorporate an indicator therein, but in which a signal line for taking out a required signal from a motor-driven screwdriver drive control circuit in the motor-driven screwdriver is led out of the motor-driven screwdriver, and information based on the electric signal is indicated on an indicator provided outside the motor-driven screwdriver body (Patent Literature 2). In this motor-driven screwdriver, tightening torque in a screw tightening operation of the motor-driven screwdriver is measured, and a control device outputs a signal indicating whether the screw tightening operation is a success or failure on the basis of the measured torque value. The success-failure signal is transmitted to the outside of the motor-driven screwdriver through the signal line, and a result of success or failure is indicated on an LED indication part.
Not all users using motor-driven screwdrivers require operation information such as the above-described information representing the motor drive status of a motor-driven screwdriver and information indicating whether screw tightening is a success or failure. Even if such information is required, pieces of required information differ for each user in most cases. Therefore, in order to meet each user's individual demand, conventional practice is to manufacture motor-driven screwdrivers as specially ordered products which enable a required signal to be taken out, or which have a function of indicating required information. There is also a case where a user wants to take out a required signal from an already used motor-driven screwdriver. In such a case, it is necessary to lead out a signal line for transmitting a signal related to an operation of the motor-driven screwdriver by applying additional machining to the motor-driven screwdriver body to provide a hole for leading out the signal line to the outside of the motor-driven screwdriver body.